Method of and means for controlling vibratory motors



g- 4, 1931- c. s. WEYANDT 1,817,403

METHOD OF AND MEANS FOR CONTROLLING VIBRATORY MOTORS Filed Nov. 2, 19255 Sheets-Sheet 1 Fig 1 10 a /1 3 6 Y 31 28 E 34 a M 29 3 T 2/ RR 17 1 927 R5 8 N M I 5 9 iii-i 32 2 i a F/g/a INVEN OR Aug. 4, 1931. c. s.WEYANDT 1,817,403

METHOD OF AND MEANS FOR CONTROLLING VIBRATORY MOTORS Filed Nov. 2, 19255 Sheets-Sheet 2 A5 f7g. O 0 IR 5' /4 /2 l 9 [SF/g. 15. "T

lNV NTOR E i (21/ Aid/75f F/g M y 'ATTORNEY Aug. 4, 1931. c. s. WEYANDT1,817,403

METHOD OF AND MEANS FOR CONTROLLING VIBRATORY MOTORS Filed Nov. 2, 19255 Sheets-Sheet 3 INVENTOR ak/s. h e a W I ATTORNEY Aug. 4, 1931. c. s.WEYANDT 1,317,403

METHOD OF AND MEANS FOR CONTROLLING VIBRAI'OR-Y MOTORS Filed Nov. 2,1925 5 Sheets-Sheet 4 NTOR INV

ATTORN EY Aug. 4, 1931. c. s. WE-YANDT METHOD OF AND MEANS FORCONTROLLING VIBRATORY MOTORS 5 Sheets-Sheet 5 Filed Nov. 2, 1925INVENTOR ar/ W A ORNEY Patented Aug. 1931 UNITED STATES PATENT OFFICECARL 8. mm, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB TO ELIO- TBIC TOOLCOMPANY, A CORPORATION OI PENNSYLVANIA IETHOD OF AND HEARS FORCONTROLLING VIBBATOB Y IOTOBS Application fled November This inventionrelates to motors having a vibrating armature, and more particularly tomeans for controlling the amplitude of movement and intensity ofpercussive effect 0 of the same.

One object of my invention is to rovide novel means in combination witha vi ratory percussive element for controlling within predeterminedlimits the percussive efi'ect thereof.

Another object of my invention is to provide meansfor operating avibratory motor having a freely oscillating armature, by currentimpulses derived by asymmetrical cond uction from a source ofalternating current.

My invention further resides inthe method .and apparatus hereindescribed and claimed.

In the present systems for controlling the vibration of industrialscreens, a relatively large electromagnet provided with aspringrestrained armature is so disposed that the armature vibrates thescreen. The magnet is energized by low frequency currents derived fromspecial generators, whereby the spring is thus'permitted to retract thearmature from the energized position of the magnet as the current passesthrough the zero values, or the magnet is energized through periodicallyoperative switching devices.

'hen the electromagnet is energized from the usual 25 or cycle light andpower circuit, the spring cannot become eliective to retract thearmature, since the magnet becomes energized at each alternation beforethe spring can actuate the armature very far. The actual movement of thearmature is hardly perceptible and is insuflicient to vibrate a screen,especially when it is loaded.

If a switching device or commutator be employed to control the periodicenergization of the electromagnet, the disadvantage of arcing betweencontact surfaces is introduced with the consequent requirements ofattention, replacement, adjustment, etc., since industrial screens ofdifferent kinds are required to shake relatively large loads, theelectromagnet for vibrating the screen may require a relatively largeenergizing current. As the value of current, which the switch orcommutator must break, increases, the arcing 2, 1925. Serial No. ",4".

increases. For that reason current switchin devices are unsatisfactoryto control the VI- bratingmagnet for the screens.

In practicing my invention, I provide a stationary control valve orunidirectional current-conducting device, such as an electron valve oran electrolytic valve, in thecircnit of the electromagnet to transmitenergy impulses corresponding substantially to the current waves of onepolarity from an alternating current circuit. During the relatively longmtervals between the impulses the elec-' tromagnet is de-energized orsubstantially de-energized, and the spring becomes effective to retractthe armature from its energized position. By properly disposing thearmature in operative relation to the screen, the movements of thearmature may be caused to effectively vibrate the screen. Thedisadvantages of switching devices and moving comm utating devices arethereby obviated.

I have illustrated the vibrating device embodying my invention inseveral embodiments which will be explained in sequence. The firstembodiment in which the vibrator is illustrated is a small sievevibrator such as is used in enameling plants for sifting enamel powders.In this embodiment thevibrator comprises a small electro-magnet whichacts upon a movable armature supported upon a flat leaf spring. The.armature, in vibrating, strikes a rod which is secured to a small screencontaining the enamel powder to be sifted. The electromagnet andarmature are disposed in a casting provided with a handle elementwhereby the operator may control the amplitude of movement of thearmature by controlling the bias of the spring which supports the armature.

Another application in which the vibrator is employed is with a screenof the drum-head type disposed in an inclined plane. This screen isnormally drawn taut and is vibrated by a suitable electro-magnetdisposed above the middle part of the screen, the armature of theelectro-magnet being secured to the screen. I

The next application in which the vibrator is illustrated is with asanding table which is employed in the manufacture of dishware. In thisapplication stacks of dishes of raw material are properly supported bysand which is packed between the respective dishes. Due to the vibrationof the table, the sand settles and packs itself firmly between thedishes or plates and serves to support the outer edges when the dishesare baked. In this application, the armature of the electro-magnet orvibrator, which I employ, strikes against a suitable striking plate onthe bottom surface of the table.

A. further applicationof the vibrating device and the controlsystemtherefor is in a casting shaker. The casting shaker is of bail-shape forlifting the finished castings. The electro-magnetic vibrating device isdisposed in the top of the bail, and, when energized, strikes the sideof the bail and causes the casting to be vibrated and the sand to beshaken therefrom.

In each of the foregoing applications, a single electro-magneticvibrating device is employed. In order to control the energization ofthe single vibrating device, I utilize the energy from analternating-current circuit and employ a unidirectional currentconducting device such as an electric valve of the two-elementelectronic type. Such a valve permits current impulses of one polarityto be transmitted to the electro-magnet from the alternating currentcircuit and suppresses impulses or current waves of opposite polarity.The electro-magnet is consequently periodically energized by distinctcurrent impulses which periodically actuate the electromagnet armature.During the intervals between the current impulses the electromagnet isde-energized and its armature is permitted to return to its initialposition.

By means of such a system, a simple economical control is provided whichis free of moving parts and commutating devices and consequent arcing.There is nothing in this system which requires care or attention such asis necessary in interrupters of the t pe which involve arcing duringtheir operation.

Still another application in which the vibrator is employed is a. sieveof the riddle type used in foundries for sifting sand. The

riddle or sieve into which the sand is thrown,

to be sifted, is suitably supported between two armatures ofelectro-magnets which are arranged to be alternately energized. Theelectro-magnets are disposed on opposite sides of the riddle or screen,and, as the corresponding armatures are attracted, the screen or riddleis shifted back and forth and the sand is sifted and rendered suitablefor use. The respective armatures are properly supported upon a leafspring at each side of the sieve.

Fig. 1 of the accompanying drawings is an assembly view of the portablevibrator I unit, partially in section and partially in ele' vation.

Fig. 2 is a )lan view, in elevation, of the control lever or controllingthe spring bias in the vibrator.

Figs. 3 and 4 are plan and end views of the control lever grip.

Fig. '5 is a plan view in elevation, of the assembled control unit forthe leaf spring.

Figs. (Sand 7 are plan and side views, in elevation, of the control armor fork element in the control unit shown in Fig. 5.

Figs. 8, 9 and 10 are side, end and plan views in elevation of thespring arms on the control unit shown in Fig. 5.

Figs. 11 and 12 are plan and side views, in elevation, of theelectro-magnet core and solenoid structure.

Figs. 13 and 14 are plan and end views, in elevation, of the laminationclamp and bumper holder for the vibrator.

Figs. 15, 16 and 17 are side, end and plan views in elevation of thebumpers against which the armature of the elect-m-magnet strikes.

Figs. 18 and 19 are front elevational and side sectional views of theimpact plate supported upon the armature to strike the rod upon whichthe sieve is supported.

Figs. 20 and 21 are plan and front views, in elevation, of the armatureplate for holdin" the laminations together.

ig. 22 is a side sectional view of the plate of Figs. 20 and 21.

Fig. 23 is a front elevational view of the leaf spring upon which thearmature is supported.

Fig. 24 is a side elevational view of the spring in Fig. 23.

Fig. 25 is a schematic view illustrating the arrangement of the sieveand the control unit therefor.

Fig. 26 is adiagrammatic view of the energizing circuit for the sieve.

Fig. 27 is a side elevational view of a sand screen suitable for foundryuse.

Fig. 28 is an elevational view of a sanding table employed in themanufacture of dishware.

Fig. 29 is a front elevational view of a casting shaker for use inshaking castings to remove the sand therefrom.

Fig. 30 is a side view partially in section, and partially in elevationof another modification of the small vibrator sieve shown in Fig. 1.

Fig. 31 is a plan view, in elevation, of the control unit in Fig. 30.

Fig. 32 is a front view, partially in elevation and partially insection, of a sand sifter suitable for foundry use.

Fig. 33 is a plan view of the clamping means employed to hold the riddlein place.

Fig. 34 is a circuit diagram illustrating the casting 1 provided with ahousing 2' and a handle portion 3. Within the housing 2 are' disposed anelectro-magnet 4, an armature '5 controlled thereby, and a leaf spring 6or equivalent vibratile member", which is anchored at one end to asupport fixed with relation to electromagnet 4 and supports the armatureat its other end. Within the housing, and adjacent the leaf spring (5,intermediate its ends, is disposed a control unit 7 by means of whichthe bias of the leaf spring is varied to govern and control theamplitude of vibration of the spring, and, consequently, of thearmature.

The operation of the control unit 7' is governed by a handle or controllever 8 which extends into the housing 2 and is controlled according tothe will of the operator who is using the sieve. As the spring biasisvaried by means of the control unit, the amplitude of vibration of thearmature is controlled. In corresponding manner the. force of the impactblow of an impact element 9, that is supported upon the spring wlth thearmature, is controlled to vary-the arrmg force impressed upon the sievewith which the v1- brator unit is employed. A small toggle switch 10 tocontrol the circuit of the magnet is disposed at the top of the housingwhere the operator may easily operate 1t by means of his thumb. v s

The electro-magnet 4 (Figs. 11 and 12) comprises a stack of laminatedfield members 12 which are held together by suitable clamping plates 13which also serve-as holders for bumpers 15 against which the armaturestrikes. The laminations are of substantially E-shape and the middlelegs support the energizing solenoid 16. The electro-n'iagnet structureis secured to and supported on the casting structure by suitable bolts17 The bumpers 15 are of the same height sub stantially as the stack oflaminations of the electro-magnet and their front surfaces are facedwith a thin layer of stellite, a non-magnetic and extremely hard'metal,which is unaffected by continuously recurring impacts.

The armature 5, as indicated in Fig. 1, consists of a stack oflaminations supported by and secured between two bronze armature plates21 (Fig. 20) that are secured to the lower en d of the leaf spring 6 bysuitable bolts 22. The bolts 22 also serve to secure the impact plate 9on the opposite side of- .cnd of a rod- 25 which is threaded into a pro-.locked into such position by a nut 27.

jection 26 on the front of the casting ailid 'l 11: rod 25 serves as asupport for a sieve through which the cnamelling powder is to be sifted.

Since a varying sifting action is desired of the sieve during operation,the force of impact of the armature against therod is variable andcontrolled by the control unit 7 in response to the action of theoperator upon the handle lever 8. The control unit 7 (Fig. 5) comprisesa rod 28, supported in the casting housing, and a cam 2!) keyed thereonwhich is moved by the handle lever 8 by means of forked or bifurcatedarms ill) also keyed on the shaft. The cam 29 is normally held in, orreturned to its initial position by two helical springs 31 which areanchored at one end upon the casting and at the other end are secured totwo arms 32 also keyed on shaft 28.

Normally, the springs 31 hold the cam 20. in its uppermost position tobias the spring 6 towards the electro-magnet. The amplitude of vibrationof the armature is thus limited'to its minimum amount. The force of theimpact of the impact element 9 against the rod 25 is correspondinglysmall. \Vhen increased sifting action is desired, the operator moves thelever 8 upwardly into the handle,'thereby moving the forked arms 3Udownward to rotate the cam in the same direction. Since the cam has areceding contour, the bias of the leaf spring will be graduallydecreased and the amplitude of vibration of the armature will becorrespondingly increased. The force of the impact. blo'ws against therod 26 will be consequenilyincreased and the sifting action of the sievewill be accelerated. As the pressure upon the lever handle isdiminished, the cam is gradually returned to its initial position andthe amplitude of vibration of the armature is correspondinglydiminished.

The action of the handle lever 8 upon the control arms 30 is effectedthrough a rod 3;). supported between the two arms 8a of the handle lever8 and disposed between the bifurcated portions of thecontrol. elements30. The lever 8 is pivoted upon a pin 34. In order that the armaturelaminations may not stick to the laminations of the electromagneticcore, the bumpers 15 are so positioned that the armature laminationswill strike the bumpers and not the core laminations ofthe-electro-magnet. Since the stellite surfaces are non-magnetic, thereis no tendency for the armature laminations to stick to the: core.Further, in view of the character of the stellite bumpers which are notaffected by recurring impacts, there is no wear which would necessitatereplacement.

The complete sieve and control unit is illustrated in .Fig. 25. Duringoperation the sieve operator usually holds or supports the combinedvibrator and sieve somewhere between the two units with one hand, andthe handle portion 3 with the other. The rod which joins the vibratorand the sieve rests in his left hand or on his left forearm. and hisright hand presses down on the handle portion to maintain the unit inbalanced horizontal position. \Vhen the switch 10 is operated. to closethe electro-magnet circuit, the magnet is energized by periodic spacedcurrent impulses which permit the armature to be withdrawn from theelectro-magnet core structure. Normally the handle lever is in itsoutermost position and the corresponding position of the cam limits themovement of the armature to a minimum. As accelerated sifting action isdesired, the bandle lever is gradually moved upward into the handleportion 3 to increase the amplitude of vibration of the armature. Theforce of impact against the rod is consequently increased with aresultant increase or acceleration of the sitting action of the sieve.

\Vhen the handle of the control unit is in non-operating position, thecam forces the spring to position the armature against the care. If theswitch is closed at that time,

the current will be limited to a minimum value by the high reactance ofthe electromagnet due to its substantially closed magnetic circuit.

My preferred system for energizing the electro-magnet to obtain spacedor periodic energizing impulses is illustrated in Fig. 26. As is shown,energy is derived from an alternating current circuit 35 to theelectro-magnet 4 through a unilateral current-co1ulacting device 36 suchas an electronic valve of the type provided with a filament and plate.The filament is maintained incandescent, to supply an electroncurrent-conducting stream, by means of an energizing transformer 37.\Vhen the circuit is of proper polarity, the valve 37 will conductcurrent to energize the electro-magnet 4. That is, when the circuitconductors have such polarity that the filament is negative with respectto the plate in the valve 36, the electro-magnet will be energized.During the period of opposite polarity, no current is transmitted by thevalve, and, consequently, the electro-magnet is not then energized.During such period, the natural bias of the leaf spring 6 withdraws thearmature from the electro-magnet and causes it to strike the rod 25 uponwhich the sieve is supported.

By means of this system I am able to utilize a standard commercial lightor power circuit of alternating current, and supply current direct tothe electro-magnet without the use of motor generators or arcingcommutating devices. There is not-hing in this system which requiresattention or care.

In Fig. 27 I have illustrated another modification of a vibratorembodying my invention. A screen 40, of the drum head type, is suitablsupported upon a framework 41, in an inc ined plane. A plate 42 issecured to the middle of the screen and also to an armature member 43,which is adapted to be vibrated by an associated electro-magnet 44. Theelectro-magnct may be connected to a suitable control circuit, such asis illustrated in Fig. 26, by conductors 45. The screen is furtherprovided with a hopper 46, into which the material which is to bescreened or sifted may be placed. The hopper may be designed so that thematerial will pass through naturally in response to gravity, or it maybe so designed as to be vibrated by the electroanagnet which alsovibrates the screen. The material which is screened will pass throughand may be collected on a shelf or suitable container 47, supportedbetween the uprights 41. A second container 48, is also provided toreceive the material which will not screen.

I have illustrated the screen of this type merely in a general way toshow the application of the vibrating device to a screen of this type.By means of the simple control system which I employ, the desiredvibration may be easily obtained without resorting to expensivefrequency changers, motorgenerator sets, or commutating devices of thetype that involve sparking and deterioration. The system which I employis simple and reliable and eliminates the wear and attention involved inthe use of commutating devices, and greatly diminishes the expense offrequency changers and motor-generator units.

In Fig. 28 I have illustrated another application in which theelectro-magnetic virator and. its control system may be readilyemployed. In that application a stack of dishes 50 are placed on asanding table 51. Sand is placed between the respective dishes and isfirm y packed in by vibrating the table 51. The vibration is effected bymeans of an electro-magnet 52, provided with a pivoted armature 53,which is adapted to strike a plate 54, secured to the bottom of thetable underneath the position where the dishes are stacked. The table isvibrated and as this is done, by the electro-magnct, the sand packsitself in firmly between the dishes, and, when they are placed in theoven to be baked, the sand supports the dishes to prevent them fromlosing their shape.

Still another application in which the single control magnet may beemployed is illustrated in Fig. 29. In that application the vibrationeffected by the electro-magnet is employed to shake the sand fromcastings after they are completed. The shaker 55 comprises a hook orgrapple 56 of bail sha having the electro-magnet disposed within thebail in such manner as to vibrate a core against the side of the bail toestablish a vibrating action therein. The vibration of the bail istransmitted to the casting 58, which is supported thereby, and the sandis consequently easily and readilv shaken from the recesses in thecasting. The grapple 56 may be suitably supported by a bail-shapedsupport 59.

In the foregoing applications I employ a single vibrating electro-magnetwhich is energized from any alternating current circuit through a singleelectron tube. By its selective action the electro-magnet transmitsunidirectional current impulses, which periodically energize theelectro-magnet, causing them to vibrate the associated armatures. Sincethe impulses are distinct and separate, the armature is permitted toreturn to its initial position each time during the interval between thesuccessive impulses. Each current impulse is thus completely utilizedand is not nullified to any extent as in these systems which employ lowfrequency alternating current, or obtain their impulses throughcommutating devices which dissi ate a great amount of the energy inarcing etween the contacting surfaces of the commutating device.

The control system of the present type is particularly advantageous inview of the amount of dust present in the air near industrial screens.The control equipment may be disposed near the screen to obviatetheexpense of conduit and cable which are necessary when arcing contactdevices are employed, since the latter must be disposed at a dlstancebecause of the dust in the surrounding air. The advantages of thepresent system are particularly advantageous where the screened materialis inflammable or explosive.

By utilizing an asymmetric valve, such as the vacuum or the electricvalve, or any other device that will transmit only preponderatinglyuni-directional energy impulses from alternating current, the expense ofspecial apparatus is obviated. Moreover, the disadvantages incident tothe operation of switching devices embodying contact members subject toarcing are likewise avoided.

My invention thus contemplates the employment of stationary, non-arcingcurrent controlling devices that will transmit preponderatinglyuni-directional energy impulses whereby the armature of anelectro-magnet may be vibrated in a predetermined desired manner.

In Figs. 30 and 31 I have illustrated another modification of a smallvibrator for an enamelling sieve. In this modification the force of theblow of the forward stroke of the armature is utilized to vibrate thesieve instead of the force of the armature in returning to its neutralposition, as occurs in effected directly by the control handle which isprovided with a cam face, and the structure is greatly simplified b theelimination of the mechanism emplo e for the indirect control in thefirst descrlbed unit. As illustrated in Figs. 30 and 31, the controlunit comprises a casting 71 provided with a main housing 72 and a handlehousing 73 which communicates with the main housing. The main housing 72contains an electro-magnet 74 comprising a core 75 consisting of a stackof laminated flux-conducting elements, an energizing coil 76, and amovable armature 77 responsive thereto; The armature 77 is secured tothe lower end of a leaf spring 78, the upper end of which is secured toa suitable support 79 on the main housing 72. An impact plate 80 issupported on the spring 78 on the side opposite the armature member 77.

The handle portion 73 of the casting is provided with a recess 82 Withinwhich a control cam 83 is disposed. The outer end of the control cam 83is pivoted on a pin 84 at the extreme end of the handle, and the innerend of the cam is provided with a gradually receding cam surface 85which is disposed to normally rest against the impact plate 80 to forcethe armature 77 into closed contact with the core 75 of theelectro-magnet. Thus normally the control cam 83 forces the armatureagainst its core and precludes any movement of the armature by thebiased spring 78. When the electro-magnet is energized, the amplitude ofvibration of the armature may be gradually increased by raising thecontrol cam upwardly into the handle. Due to the receding surface of thecam, against which the impact block will strike, the space within whichthe armature may vibrate due to the actuation of the electromagnet andthe receding force of the spring 78 will be increased when the cam ismoved upwardly into the handle.

The energization of the electro-magnet 76 is controlled by a smallswitch'86 which is disposed in the upper portion of the castin directlyabove where the operators thum will rest. The circuit for energizing theelectro-magnet is the same as has already been described and illustratedin Fig. 26.

At the front end of the main housing is disposed a threaded socket 88which may be integral with the casting or in the form of a flangedsleeve secured to the casting. The threaded opening is adapted toaccomodate and receive a threaded rod 90, the outer end of which issecured to and supports the sieve which it is desired to vibrate. Theinner end of the rod 90 abuts against the coil laminations of theelectro-ma-gnet, and, when the latter are struck by the armature,theforce of such impact is transmitted to the rod 90 and in turn istransmitted to the sieve to cause vibration thereof. Thus, it will beobvious that b means of the arrangement which Ihave il ustrated in thismodification,

the amplitude of vibration of the armature may be easily controlled bythe operator to vary the force of the impact blows transmitted to therod which supports the sieve, to effect vibration thereof.

In order to prevent the armature laminations sticking to the corelaminations, I provide two stellite-faced bumpers 91 against which animpact clement 77a may strike;

The element is supported on the spring 78 together with the armature 77.The bumpers 91 are supported between two plates 92 which also hold thecore laminations together in a tight unit. Since the rod 90 reststightly against the core laminations, the force is transmitted directlywithout any tendency to displace the electro-magnet.

Another application in which I have applied the vibrating device and theimproved control system is a sand sifter or riddle for use in foundrywork. As illustrated in Fig. 32, showing an assembly view of a vibratingsi-eve or sand sifter, the sand sitter 100 comprises two arms orsupports 101 forming a yoke between which the screen or riddle 102 issupported. The arms 101 are concave on the inside and at the lower endare each provided with a housing 103. Each housing 103 accommodates anelectro-magnet 104 comprising a solenoid 105 and a stack of laminations106. The electro-magnets are rigidly secured to and supported by therespective yokes by bolts 107. Each electro-magnet is provided with anarmature 108 consisting of a stack of laminations 109 secured betweentwo plates 110. The laminations 109 and the clamping plates 110 aresecured to and supported at one end of a leaf spring 111, the other endof which isanchored securely to a boss 112 on the inside of the yoke,directly above the electro-magnet. The armatures 108 are spaced andmaintained a definite distance from each other by means of two rods 113which also serve as supports for the riddle 102 and a clamping ring 114disposed around the riddle. The yokes are rigidly secured and spaced tomaintain a definite distance between them by means of two rods 115. Adefinite pre-determined airgap is thus assured between each armature andits electro-magnet. The leaf springs 111 serve both as supports for thearmatures and the sieve, and also as retrieving springs which tend tocenter the sieve between the electro-magnets.

The upper end of the two supports 101 are rigidly sedured to andsupported by a base plate 116 which, together with the supports 101, issupported by a hanger or bail 117. The base plate 116 serves to supporta control box containing the control apparatus for the energization ofthe electromagnets, as

will be presently described.

The clamping ring 114 is provided with an adjustable clamping device118, as illustrated in Fig. 33, and permits the insertion of riddles ofdifferent size mesh screen. The system for controlling the cnergizationof the electro-lnagnets is illustrated in Fig. 34. As' thereillustrated, energy is derived from an alternating current circuit 120and transmitted through to the respective solenoids of theelcctro-magnets 104 and 104a by two .unidirectional current-conductingdevices,

such as electron tubes 126 and 127, of the type embodying anincandescent filament as the cathode and a plate as the anode. Thefilaments of the two valves are energized through a small transformer128 which is merely of sufiicient current-carrying capacity to energizethe filaments. The respective circuits including the valves 126 and and,consequently, transmits current to the electro-magnet 104a to energizethe same. Thus, as the polarity of the circuit 120 changes, the valvesalternately conduct current to their associated electro-magnets, whichbecome energized alternately and influence the associated armatures tovibrate the riddle in synchronism with the frequency of the derivedcurrent.

- By means of this system all arcing devices are obviated and onlystationary control apparatus is used. The cost of such a system isrelatively small and permits the use of current or electrical energythat may be derived from the usual light orv power circuit ofalternating current.

This system illustrates the use of two electric valves whereby twoelectro-magnets may be alternately energized to effect the alternatemovement or vibration of a desired member. I have illustrated thissystem as applied to the operating of a foundry sieve of the type inwhich the positive alternate movement of the sieve is desired. It isobvious that thesame system, employin two electro-magnets that may bealternate y energized, may be applied to any device which it is desiredto vibrate in both directions by positive action.

These systems which I have illustrated herein can be employed in variousapplications to which I have applied them, and are articularlyadvantageous where unskilled abor is imployed as no care and attentionare requi for these systems. My invention is not limited to the specificarrangement of elements or construction details that are illustrated,but may be variously modified without departing from the spirit andscope thereof as set forth in the appended claims.

I claim as my invention:

1. A vibrating device comprising an electro-magnet, a casing thereforincluding a handle, an armature for the electro-magnet, a biasingsupport therefor, and a pivoted lcver cooperating with the handle andextending into the casing to control the opera-' tion of the support.

2. A percussive device comprising an electro-magnet embodying a magneticstructure, a movable member responsive thereto and adapted to transmitthe force of the blow through the structure to a suitable tool, aflexing support for the movable member, and a pivoted lever controllableby the operator for varying the stroke of the movable member.

3. A percussive device comprising an electro-magnet, a vibratory memberresponsive thereto, a resilient support forming sole mounting structurefor said vibratory memher, and cam actuating means for varying thetension of said resilient support and thereby controlling the intensityof percussive effect of said member.

4. In a percussive device, a casing, an electro-magnet enclosed thereby,a resiliently mounted vibratory armature and percussive element adaptedto be actuated by said electromagnet, means operable to control thedegree of vibration of said percussive element, and a pivoted levercontrolled from the exterior of said casing and extending into the sameinto engaging relation with said cam means to effect controllingoperation of the latter.

5. In a percussive device, an electromagnet, a combined armature andpercussive element, a resilient support forming sole mountin structurefor said element, and means for a fecting the tension of said resilientsupport and thereby varying the intensity of percussive effect of saidelement, said means comprising a cam element normally biased byresilient means into engagement with said support for permittingvibration thereof to a varying degree.

6. In a percussive device, an electromagnet, a vibratory percussiveelement, coopcrating therewith and having a resilient support, means forvarying the degree of vibration of said element comprising a pivoted camnormally biased by resilient means into engagement with said resilientsupport, and manually-operable means for controlling the position ofsaid cam and thereb controlling the degree of vibration of said e ement.

7. In vibratory apparatus of the character described, an armature,spring means biasing said armature in a given direction, electromagneticmeans operable to impart move- CARL S. WEYANDT.

